Curving method and apparatus for ridged sheet material

ABSTRACT

Method and apparatus for forming ridged sheet material into arcuate shape. Sheet material having an elongated major ridge or corrugation extending along a line is curved along said line by progressive formation therealong of a series of corrugations or pleats directed substantially normal to said line.

United States Patent Davis CURVING NIETHOD AND APPARATUS FOR RIDGEDSHEET MATERIAL Inventor: Paul K. Davis, Alameda, Calif.

Assignee: Pacific Roller Die Co., Inc., Hayward,

Calif.

Filed: Mar. 16, 1970 Appl. No.: 19,974

US. Cl ..72/307, 72/385, 72/379 Int. Cl ..B2ld 11/04 Field of Search..72/307, 385, 166, 169, 196, 72/379; 113/116 R References Cited UNITEDSTATES PATENTS 6/1923 Lennox ..72/307 51 May 23, 1972 1,617,069 2/1927McLaughlin ..72/166 496,354 4/1893 Fairman ..72/307 3,472,418 10/ l 969Ullman ....220/72 1,771,028 7/1930 Bronson et al. .....72/379 999,3908/191 1 McMartin ..72/379 Rl6,115 7/1925 Schlafly ..72/379 2,775,28412/1956 Hermann ..72/187 Primary Examiner-Charles W. Lanham AssistantExaminerMichael J. Keenan AttorneyBoyken, Mohler, Foster & SchwabABSIRACT Method and apparatus for forming ridged sheet material intoarcuate shape. Sheet material having an elongated major ridge orcorrugation extending along a line is curved along said line byprogressive formation therealong of a series of corrugations or pleatsdirected substantially normal to said line.

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BACKGROUND OF THE INVENTION This invention relates to forming of metalsheet material or other plastically deformable materials, and moreparticularly to the curving of an elongated longitudinally ridged sheetmetal workpiece into arcuate shape suitable for use as a high strengthstructural member.

The curving method and apparatus of this invention are advantageouslyutilized in formation of arcuate sheet metal panels for construction ofarched structures such as corrugated waterway conduit or quonsetbuilding structures. Commonly, individual panels employed in suchstructures have one or a series of elongated ridges or corrugations,hereinafter termed the major corrugation(s), and are curved in thedirection of extent of the corrugations about a radius corresponding tothe desired radius of curvature of the completed structure. Knowncurving methods and apparatus are severely limited as to maximumthickness of sheet material, cross-sectional profile of the major ridgeor corrugation, or degree of curvature obtainable. For example,objectionable buckling or other spurious deformation occurs if it isattempted to employ conventional methods and apparatus to curve acorrugated metal sheet along the direction of corrugation when thecorrugation depth is of the order of 1 foot. The inherent limitations inprior art methods and apparatus preclude formation of curved structuralpanel of exceedingly high strength, since increased strength resultsfrom increased sheet thickness and greater depth of the majorcorrugation.

SUMMARY OF THE INVENTION In this invention for curving ridged sheetmaterial, which may take the form of a sheet metal workpiece formed withone or a series of major corrugations or ridges extending in alongitudinal direction, a series of secondary corrugations or pleats isprogressively formed along the direction of extent of the longitudinallyextending ridge or ridges. The secondary corrugations are directedtransversely, i.e., substantially normal to the direction of extent ofthe major corrugation and function as gathers or pleats enabling thematerial to be curved along the line of extent of the major corrugationwithout objectionable buckling or other undesired deformation. Thecurvature which occurs during progressive formation of the secondarycorrugations is most significantly affected by the spacing andconfiguration of the secondary corrugations, and may accurately becontrolled by adjustment of such spacing and configuration. The methodand apparatus of this invention obviates the problem of buckling orinterference between adjacent deformed sheet portions, and thus rendersit feasible to obtain curved structural panels of higher strength thenheretofore obtainable, from sheet material of greater thickness and withmajor corrugations having more pronounced cross-sectional profiles. Asteel sheet workpiece approximately one-eighth inch thick and having amajor corrugation 1 foot in depth and 2 feet in pitch is representative,but thicker materials with more pronounced major corrugations may beaccommodated.

It is therefore, an object of this invention to provide a novel methodof and apparatus for curving ridged sheet material in the direction ofextent of the ridge.

Another object of the invention is to provide a method of and apparatusfor curving ridged sheet material along the length of the ridge, whichmaterial is more resistant to such curving than materials heretoforecurved, because of greater thickness or a more pronounced ridge therein.

A further object of the invention is the provision of a method of andapparatus for curving ridged sheet material along the length of theridge accurately to different desired degrees of curvature.

Additional objects of the invention are to provide, a method of andapparatus for curving a ridged sheet workpiece along the length of theridge so as to avoid buckling cf material, a

method and apparatus that will accommodate a workpiece that is unlimitedas to length, a method and apparatus that will not weaken the material,and an exceedingly rapid and efficient curving method and apparatus.

Other objects and advantages of the invention will become I apparentfrom the following description of a preferred embodiment of theinvention.

DESCRIPTION OF THE FIGURES FIG. 1 is an overall, partially schematic,side view of a preferred form of apparatus embodying the invention, withparts broken away for purposes of clarity;

FIG. 2 is a side, partly sectional view of the press assembly portion ofthe apparatus of FIG. 1;

FIG. 3 is a fragmentary, side view of the input end of the apparatus ofFIG. 1;

FIG. 4 is an end view of the input end illustrated in FIG. 3, as viewedfrom line 4-4 thereof;

FIG. 5 is an end view of the press assembly portion of FIG. 2, as viewedfrom line 5-5 thereof with parts removed for purposes of clarity;

FIG. 6 is a fragmentary, sectional view of a portion of the apparatus ofFIG. 2 substantially as viewed along line 6-6 thereof;

FIG. 7 is a view similar to FIG. 6, but with parts differentlypositioned as at termination of a pressing operation;

FIG. 8 illustrates one form of workpiece on which may be performed themethod of this invention;

FIG. 9 is a fragmentary view of adjustable punch plate mounting means inthe assembly of FIG. 2;

FIG. 10 is a fragmentary, sectional view taken along line 10-10 ofFIG.9;

FIG. 11 is a cross-sectional view of a portion of the feed means of theapparatus illustrated in FIG. 2, as viewed substantially from line 1 1-11 thereof;

FIG. 12 is a fragmentary view of a braking wheel assembly as seen fromline 12-12 of FIG. 11;

FIG. 13 is a fragmentary sectional view of the upper portion of diemembers of the assembly of FIG. 2, showing their initial position asseen in FIG. 2, but on an enlarged scale relative thereto;

FIG. 14 illustrates the parts of FIG. 13 in position during anintermediate point in a pressing operation;

FIG. 15 illustrates the parts of FIGS. 13 and 14 at completion of apressing operation;

FIG. 16 is a fragmentary view of a material hold-down assembly takenalong line 16-16 of FIG. 5;

FIG. 17 is a side view of a portion of a curved structural panel formedby performing the invention; and

FIG. 18 is a cross-sectional view of the structural panel of FIG. 17,taken along line 18-18 thereof.

DESCRIPTION OF A PREFERRED EMBODIMENT In detail, with reference to FIG.1, a preferred embodiment of the apparatus of this invention comprises afeed means 10 for advancing a sheet material workpiece 11 along a pathof travel, toward the right in FIG. 1, through a press assembly 12wherein curving is accomplished. After passage through press assembly 12the curved structural panel formed from workpiece 11 is removed from thecurving apparatus past the output end 13 for further handling.

workpiece 11 may take the form of an elongated sheet metal strip (FIG.8) having a central longitudinally extending upwardly directed majorridge or corrugation 14, between curved outwardly flared side edgeportions 15. It is supported for travel along a horizontal path on feedmeans 10 comprising a pair of horizontally spaced parallel channelmembers 16 (FIGS. 3, 4) extending in the direction of the feed path andeach supported at one end by a vertical member 17 (FIG. 3) and proximatethe opposite end nearest press assembly 12 by a vertical member 18 (FIG.2), members 17, 18, in turn, being supported on a base 19 (FIGS. 2, 3).At regular intervals along channel members 16 are mounted opposed pairsof bearing blocks 21 (FIGS. 3, 4 and 11) between which extend shafts 22(FIGS. 3, 4) for rotation in said bearing blocks. A shaft 22a in bearingblocks 21 nearest press assembly 12 is of different broken construction,as will be described. Midway along each shaft 22 is fixed a sprocketwheel 23, so that there is provided a plurality of aligned sprocketwheels 23 around which extends a continuous feed chain 24.

A bracket member 25 (FIGS. 2, 3, 4) is attached to a link of chain 24and includes an elongated bracket portion 26 spaced outwardly of chain24 and provided with an aperture 27 (FIG. 3) for receiving a removablepin 28 (FIGS. 2, 3, 4). A bracket member 30 (FIG. 1) similar to bracketmember 25 is similarly attached to a link of chain 24 at a point remotefrom bracket member 25 whereby one such bracket member will be on theupper run of chains 24 proximate one end of feed means when the otherbracket member is on the lower run proximate the opposite end of feedmeans 10 (FIG. 1). The upper portion 29 of each vertical member 17 (FIG.4) extends above channel member 16 and has fixed to its upper end theend of a tubular member 32 that extends in the direction of the materialfeed path to a point of attachment at the opposite end 34 (FIG. 2) to avertical plate 35 (FIGS. 2, 5) which, as will hereinafter be described,serves as a die plate. Vertical plate 35 is mounted on a horizontalplate 36 which is on the upper surface of base 19 so that the uppermostsurface of plate 35 is at the same level as the upper surface of bracketmembers 25, 30 when they are on the upper run of chain 24. Whenworkpiece 11 is disposed with the peak of major corrugation 14 supportedon the upper one of bracket members 25, 30 and on the uppermost surfaceof vertical plate 35, the pair of tubular members 32 provide additionalguide support symmetrically at each side of the corrugation peak.

One end of a crank arm 37 (FIGS. 2, 11) is keyed on the shaft 22anearest die plate 35 at a point on the shaft adjacent one bearing block21 (left-hand bearing block 21 in FIG. 11), and the opposite end ofcrank arm 37 is connected to a yoke 38 at the outer end of a piston rod39 associated with a hydraulic cylinder 42 (FIG. 2). Also on shaft 22abetween arm 37 and sprocket wheel 23 is a ratchet wheel assembly 40(FIG. 1 1) of conventional construction. Arm 37 and an adjacent ratchetwheel portion 50 are on a common shaft portion 51, of shaft 220 havingan end terminating within ratchet wheel portion 50. Ratchet wheelportion 60 and sprocket wheel 23 are on a common shaft portion 61 havingan end terminating within ratchet wheel portion 60. When piston rod 39is retracted arm 37 is rotated (clock-wise in FIG. 2) causingcorresponding rotation of shaft portion 51 and ratchet wheel portion 50(FIG. 11) and through said ratchet wheel portion the ratchet wheelportion 60, shaft portion 61 and sprocket wheel 23. When piston rod 39is extended to cause reverse rotation of crank arm 37 the portions ofratchet wheel assembly 40 are not interengaged and sprocket wheel 23 isnot rotated in the reverse direction. Thus, sprocket wheel 23 is adaptedto be driven only in the direction for advancing chain 24. To preventoverride of chain 24 beyond the desired distance of advancement abraking wheel 70 (FIGS. 11, 12) on shaft portion 61 carries a strap 71(FIG. 12) that is attached at one end 137 to vertical member 138 on base19. The opposite end 139 of strap 71 is connected to a rod 140 slidinglyreceived through an aperture 141 in bracket 142 on member 138, and ahelical spring 143 is carried on the threaded free end 144 of rod 140between bracket 141 and an adjusting nut 145. When nut 145 is threadedtoward bracket 141 drag on braking wheel 70 by frictional contact withstrap 71 is increased, and with nut 145 the drag is adjusted so as topermit shaft portion 61 to be rotated by crank arm 37 and associatedparts without undersired override.

Press assembly 12 (FIGS. 1, 2 and 5) provides a corrugating means orstation and includes a vertical frame comprising a pair of verticalframe members 44 (FIGS. 2, S) spaced in the direction of the feed pathand each extending upwardly from a point of support on the ground at theside of base 19. A pair of similar frame members 45 (only one of whichis shown in FIGS. 2, 5) are opposite frame members 44 at the oppositeside of base 19. Horizontal cross-members 46, 48 extend between framemembers 44, 45, respectively, at an elevated portion thereof, andrespectively include a lower inwardly directed horizontal flange 47, 49(FIG. 2). A pair of opposed, horizontally extending channel members 52are connected between flanges 47, 49 respectively of cross-members 46,48 and have bolted thereon the lower end of a heavy-duty hydrauliccylinder 53 having a piston rod 54 depending between channel members 52.The upper end of the frame includes suitable additional frame members ofconventional construction to assure necessary strength. Cylinder 53 issupplied with fluid through pipe 41.

Fixed to the lower end 55 of piston rod 54 (FIG. 2) and extendingparallel to channel members 52 is a horizontally disposed mounting bar56, to the underside of which is connected a box member 57 (FIGS. 2, 5and 9). Box member 57 extends substantially fully the distance betweenthe pairs of frame members 44 and 45, and at one end 58 (FIG. 5) isslidingly received between the inwardly directed plates 59 (FIGS. 2 and5) of a pair of guide brackets 62 on frame members 44, and at the otherend 63 (FIGS. 5 and 9) is similarly received between the plates 64 (FIG.5) of guide brackets 65. Box member 57 is adjustably connected to bar 56for varying the spacing therebetween, by means comprising a pair ofconnecting bolts 66 (FIGS. 9 and 10), one on each side of piston rod 54.Bolt 66 is slidingly received in an aperture 67 (FIG. 9) in bar 56 andis threadedly received through a nut 68 fixed to the interior surface ofthe upper wall 69 of box member 57. At each end portion of bar 56 a pairof adjusting bolts 72 (FIGS. 9 and 10), are threaded through a nut 73and through bar 56. To adjust spacing between bar 56 and box member 57bolts 66 and nuts 73 are backed from the upper surface of bar 56, bolts72 are then threaded to project below bar 56 the distance of desiredspacing between the bar and box member 57, and nuts 73 and bolts 56 thenare tightened to lock parts in place.

Bolted to the undersurface of the lower wall of box member 57 (FIGS. 2and 5) by bolts 76 is the horizontally disposed mounting plate 77 of avertical punch plate 78 (FIGS. 2, 5, 6 and 7) having pairs of verticalreinforcing ribs 79 (FIGS. 2 and 5). The downwardly facing workingsurface or punch surface 81 of punch plate 78 is concavely curvedsubstantially fully between reinforcing ribs 79, but adjacent said ribsincludes reversely curved portions 82 (FIGS. 5, 6 and 7). In crosssection through plate 78 punch surface 81 is rounded (FIG. 2) as morefully described below.

On horizontal plate 36 (FIGS. 2, 5, 6, and 7) directly below punch plate78 is a vertical die spacer plate 85 of a die assembly 83 positionedbetween die plate 35, and a vertically slidable die plate 86, againstthe opposite face of which is an end plate 87 (FIG. 2). The die surface89 of die plate 35 (FIGS. 2, 5 and 6) is shaped to conform to thecontour of workpiece 11 (FIGS. 5, 6, 7) and is rounded at the cornerfacing toward punch plate 78 (FIGS. 2, 13, 14 and 15). Spacer plate 85having a flat edge surface 93 is shaped generally similarly to plate 35,but has smaller dimensions so that said edge surface is located inwardlyof the edge surface 89 of plate 35, and it includes a pair of loweroutwardly directed tab portions 92 (FIGS. 6, 7). Plate 85 is ofsubstantially the same thickness as punch plate 78. The convex diesurface 91 of slidable die plate 86 corresponds to the shape of diesurface 89 of plate 35. At each corner of the bottom edge 94 of plate 86(FIGS. 5, 6, and 7) is a bevel portion 95 which is adapted to be engagedby the leading wedge surface 96 of a lifting wedge 88 provided forelevating plate 86. When fully elevated by wedges 88 die surface 95(FIGS. 6, 7, 13, 14 and 15) is at the same level as die surface 89 ofplate 35. In cross section through plate 86 die surface 91 is fullyrounded (FIGS. 2, 13, 14 and 15). End plate 87 (FIGS. 2, 5) is similarto spacer plate 85 and includes corresponding tab portions 99 (FIG. 5).

Lifting wedges 88 are mounted in opposed relation for sliding on theupper surface of horizontal plate 36 (FIGS. 5, 6 and 7) and along loweredge 94 of plate 86. Each wedge 88 is fixed at the end of a piston rod97 (FIGS. 6 and 7) associated with a horizontally mounted double actinghydraulic cylinder 98 of conventional construction, and is slidablyreceived between tab portions 92 and 99 of plates 85 and 87respectively. To the outer end of each tab portion 92 on spacer plate 85is bolted a connecting bar 100 (FIG. 7) which extends to connect withthe end plate 103 of hydraulic cylinder 98 (FIGS. 2, 5, 6 and 7).Similar connecting bars 104 on tab portions 99 (FIG. 5) also areconnected to end plate 103 for mounting hydraulic cylinder 98.

Lubricating means are provided to facilitate sliding of slidable dieplate 86 between spacer plate 85 and end plate 87, for which purposeplate 86 is provided with an upper vertically extending slot 105 (FIGS.6 and 7) and a pair of narrower but equally long lower slots 106.Apertures in the other plates 35, 85 are located to be aligned with theupper end of slots 105, 106 when plate 86 is in its lowermost position,and all plates of die assembly 83 are connected by an upper connectorassembly 107 and a pair of lower connector assemblies (FIG. 2).Connector assembly 107 includes a threaded end portion 109 threadedlyreceived in die plate 35, a cylindrical body portion 110 extendingthrough spacer plate 85 and slidable die plate 86 and of the samediameter as the rounded ends 113 of slot 105, and a shank portion 114extending through end plate 87. A central bore 115 extends through-shankportion 114 and partially through body portion 110 and communicates withthe interior of a hollow nut 116 threaded against the outer face of endplate 87 and mounting a fitting 117 within which is the end of hydraulictubing 118. Within bore 115 at a point midway through slot 105 inslidable die plate 86 are transversely extending ports 119, twohorizontal and two vertical, communicating between bore 115 and theinterior of slot 105 for introduction of lubricating fluid into saidslot 105. The construction of each connector assembly 108 (FIG. 2) issimilar to connector assembly 107, except the various portions aresmaller in diameter. Connector assemblies 108 includes a body portion122 extending through slot 106, corresponding to body portion 1 throughslot 105. The interiors of connector assembly 108 and slot 106communicate with hydraulic tubing 124 for introduction of lubricatingfluid into said slot. Slidable die plate 86 is retained in its lowermostposition with bottom edge 94 spaced slightly from plate 36 (FIG. 6) byconnector assemblies 107, 108 engaging the upper rounded slot end 113 ofslot 105 and the upper rounded ends 123 of slots 106, respectively.Slots 105, 106 are of sufircient length to permit plate 86 to be fullyelevated by wedges 88 without interference between the lower ends ofsaid slots and connector assemblies 107, 108.

On base 19 at the output side of press assembly 12 a stop plate 125(FIG. 2) is connected at an end 126 for pivoting about a horizontal pin127 between a horizontal position and a vertical position parallel tothe plates of die assembly 83 and across the feed path of workpiece 11,under the action of a conventional hydraulic cylinder 128 pivotallyconnected to plate 125 through yoke 129, pin 130 and bracket 131. Whenstop plate 125 is in the vertical position 125 (FIG. 2) workpiece 11 maybe abutted against the plate to set initial positioning of theworkpiece. The plate is withdrawn during the curving operation. Duringthe pressing step of the curving operation the lower portion ofworkpiece 1 l is held against die plates 35, 86 by a pair of hold-downbars 134 (FIGS. 5, 7 and 16) each depending from a mounting bracket 135on the lower corner of punch plate 78 and including a cylindrical bar134 adapted to engage workpiece 11 immediately above edge portion 15.

In operation, one of the pair of bracket members 25, on chain 24 islocated at the end of the upper run of said chain remote from pressassembly 12 (FIG. 1), and workpiece 11 is placed on tubular members 32with its trailing edge (relative to the direction of feed) extendingacross elongated bracket portion 26. An aperture 31 in the trailing edgeportion of workpiece 11 (FIG. 3) is aligned with aperture 27 in bracketmember 25 and pin 28 is inserted therethrough. Stop plate 12 is in thevertical position, and chain 24 with workpiece 11 is advanced byhydraulic cylinder 42 until the leading edge of workpiece 11 is againstsaid plate 125 and workpiece 11 is correctly positioned within pressassembly 12 for initiating the first pressing operation. Thereafter stopplate 125 is retracted from the feed path by hydraulic cylinder 128. Theterminal points of travel of punch plate 78 are set through adjustmentof spacing between bar 56 on piston rod 54 and box member 57 (FIG. 9). I

Press assembly 12 is then actuated for causing hydraulic cylinder 54 todescend with punch plate 78 to form the first corrugation or pleat 132(FIGS. 2, 18, 19.) in workpiece 11 in conjunction with die assembly 83.In FIG. 7 punch plate 78 is illustrated in the pressing position.Thereafter, piston rod 54 with punch plate 78 ascend, and simultaneouslyworkpiece 11 is advanced into position for a succeeding pressingoperation by retraction of piston rod 39 of hydraulic cylinder 42 (FIG.2). Because of ratchet wheel assembly 40 on shaft 221, extension ofpiston rod 39 causes no reverse rotation of sprocket wheel 23 thereon.Braking wheel 70 assures workpiece 11 will advance the predetermineddesired distance without override, and such distance may be adjusted byadjusting the distance of travel of piston rod 39. During the pressingof workpiece 11 it is additionally held against die assembly 83 in placeby holddown bars 134 (FIG. 5).

When punch plate 78 is in the initial elevated position, the plates ofdie assembly 83 are positioned as shown in FIGS. 2, 5, 6 and 13. Liftingwedges 88 are withdrawn from engagement with slidable die plate 86 andsaid plate is supported by connector members 107, 108 with the upper diesurface 95 thereof below the upper surfaces of spacer plate and endplate 87 (FIGS. 13). As punch plate 78 descends hydraulic cylinders 98are actuated, and lifting wedges 88 are extended initially to contactbeveled corner portion to elevate plate 86 and then to slide along loweredge 94 (FIG. 7). Die surface 91 of die plate 86 is level with diesurface 89 of die plate 35 (FIG. 14). When punch plate 78 has descendedto the pressing position (FIG. 15) die surface 81 thereof is receivedbetween rounded die surfaces 89 and 95 respectively of plates 35 and 86.All such die surfaces are rounded to correspond to the desired contourof corrugation 132.

Following the pressing operation punch plate 78 is elevated by hydrauliccylinder 53, and simultaneously lifting wedges 88 are withdrawn wherebyplate 86 descends to permit advancement of workpiece 11 for a succeedingpressing operation. Lubricating fluid continuously is introduced underpressure into the interior of slots and 106 in plate 86 through lines118 and 124 (FIG. 5). When die plate 86 is moving upwardly the volume ofthe interior of the lower portion of slots 105 and 106 below theconnector assemblies 107, 108 decreases and the fluid therein is forcedbetween the die plates under high pressure to provide effectivelubrication. On descent of plate 86 a similar pumping effect is obtainedwith fluid confined within the portion of slots 105 and 106 above theconnector assemblies. The cycle is repeated until all desiredcorrugations 132 are formed.

Referring to FIG. 8, one form of workpiece 11 which advantageously hasbeen utilized is formed of a strip of galvanized steel sheet having amajor corrugation approximately 14 inches in depth, and with an overallwidth of approximately 24 inches including the two side edge portions 15of approximately 2 inches width from the lower terminal point of thestraight sloping side of major corrugation 14 to the edge of saidworkpiece. It is a desirable feature of this invention that theworkpiece may be unlimited as to length. To obtain an arcuate structuralpanel 5 (FIGS. l7, l8) suitable for construction of arched structures ofapproximately 25 feet radius it has been found highly satisfactory toform corrugations or pleats 132 having a pitch of approximately 2 inchesand a depth of approximately one-half inch, at the peak of majorcorrugation 14. Utilizing punch plate 78 and die assembly 83 as hereindescribed, the corrugation 132 extends approximately twothirds thedistance of the sloping side of major corrugation 14, and isprogressively shallower from the peak of major corrugation 14 to itslowest point 133 (FIGS. 17 and 18). With the corrugations 132 so formed,workpiece 11 will accurately be curved in a longitudinal direction abouta radius of 25 feet. Different degrees of curvature may be obtained bychanging the pitch or depth or both of corrugations 132 formed. Curvedpanel is utilized by bolting or otherwise fastening with similar panels5 feet (FIGS. 18) in side by side fashion at edge portion and end toend.

It is to be understood that the claims appended hereto are intended tocover all changes and modifications of the example herein chosen forpurposes of disclosure which do not depart from the spirit and scope ofthe invention, including method and apparatus in which a series ofcorrugations is progressively formed in a stationary workpiece bytraveling forming means. No restriction is to be implied as to theinitial configuration of the ridged workpiece. Alternative means forforming the corrugations or pleats may include roller devices, and whenit is necessary to feed a workpiece it may be supported and advanced bya traveling die member, or alternatively, an intermittently rotatedpressure roller may frictionally engage said workpiece for advancing it.

I claim:

1. A method of curving sheet material having at least one elongatedridge, to form an arc therein in the direction of extent of said ridge,comprising:

a. providing a corrugating station;

b. relatively moving said sheet material and said corrugating stationalong the longitudinal axis of said ridge;

0. progressively forming along said ridge a series of corrugations ofpredetermined depth, said corrugations each being directed transverselyof said ridge;

d. at said corrugating station said corrugations each being formed by:

. supporting said material at the surface thereof external to said areto be formed therein against a first die surface,

2. supporting said material at said surface thereof against a second diesurface spaced from said first die surface along said axis,

3. intercepting the opposite surface of said material and defonning saidmaterial against the said surfaces with a punch surface locatedtherebetween, and

. thereafter releasing said material by moving said punch surface and atleast one of said die surfaces from said material in opposite directionsnormal to said axis for a distance at least as great as saidpredetermined depth.

2. The method of claim 1, including:

f. forming said corrugations regularly spaced along said ridge, forcurving said sheet material about a single point.

3. A method of curving an elongated strip having at least one roundedridge extending longitudinally of said strip between opposite ends ofsaid strip, to form an arc therein in the direction of extent of saidridge, comprising:

a. supporting said strip for movement along a longitudinal path oftravel;

b. providing a corrugating station at a location along said path;

c. intermittently longitudinally advancing said strip to positionsuccessive portions of said strip at said corrugating station; and

d. at said corrugating station forming corrugations in each of saidsuccessive portions of said ridge, extending transversely thereof by;

l. at spaced points along said portions, supporting same at the surfacethereof external to said are to be formed in said strip against thesurface of a first die element,

2. supporting same at said surface thereof against the surface of asecond die element reciprocable in directions normal to said path, and3. intemiittently intercepting said path at a point between said spacedpoints from the side thereof internal of said are to be formed in saidstrip with a surface of a corrugating element reciprocable in directionsnormal to said path; and

e. thereafter releasing said portions by retracting at least said firstdie element and said corrugating element in opposite directions normalto said path for a distance at least as great as said predetermineddepth for permitting advancement of succeeding portions along said path.

4. Apparatus for curving an elongated strip having a rounded ridgeextending longitudinally of said strip, to form an arc therein in thedirection of extent of said ridge, comprismg:

a. support means for supporting said strip for movement in a path alongthe longitudinal axis of said strip;

b. corrugating means positioned at a point along said path adapted forforming a corrugation of predetermined depth in said ridge transverselythereof;

c. Feed means for intermittently advancing said strip along said pathand positioning said portions of said ridge at said point;

d. actuating means for actuating said corrugating means for forming acorrugation in each of said successive portions of said ridge;

e. said corrugating means including,

1. a punch member at the side of said strip internal to the arc to beformed therein and reciprocable in directions normal to said path,

2. a die assembly at the opposite side of said strip in opposedrelationship to said punch member,

3. said punch member having a punch surface arcuately shapedtransversely of said path for forming said corrugation transversely insaid ridge, and

4. said die assembly including a portion retractable in a directionnormal to said path a distance at least as great as said depth.

5. The apparatus of claim 4, wherein:

f. said die assembly includes a die member reciprocable in directionsnormal to said path for positioning against the surface of said ridge atsaid opposite side of said strip during said forming and retractiontherefrom for a distance at least as great as said depth prior to saidadvancing.

6. The apparatus of claim 5, including:

g. at least one reciprocable wedge member engageable with sad die memberfor alternately positively moving said die member into position againstsaid surface of said ridge and permitting retraction therefrom; and

h. means for imparting reciprocating motion to said wedge member.

7. The apparatus of claim 5, including:

g. means for imparting reciprocating motion to said die member in saiddirections normal to said path;

h. a stationary member at each of two opposite sides of said die memberin slidable contact therewith;

i. a source of lubricating fluid;

j. at least one aperture defined in said die member having a fixeddimension normal to the directions of movement thereof;

k. a conduit for conducting said fluid to within said aperture includinga stationary conduit portion within said aperture substantiallycoextensive with said fixed dimension;

1. said fluid being positively urged between opposed surfaces of saidstationary members and said die member by said reciprocating motion ofsaid die member for lubricating said surfaces.

1. A method of curving sheet material having at least one elongatedridge, to form an arc therein in the direction of extent of said ridge,comprising: a. providing a corrugating station; b. relatively movingsaid sheet material and said corrugating station along the longitudinalaxis of said ridge; c. progressively forming along said ridge a seriesof corrugations of predetermined depth, said corrugations each beingdirected transversely of said ridge; d. at saId corrugating station saidcorrugations each being formed by:
 1. supporting said material at thesurface thereof external to said arc to be formed therein against afirst die surface,
 2. supporting said material at said surface thereofagainst a second die surface spaced from said first die surface alongsaid axis,
 3. intercepting the opposite surface of said material anddeforming said material against the said surfaces with a punch surfacelocated therebetween, and e. thereafter releasing said material bymoving said punch surface and at least one of said die surfaces fromsaid material in opposite directions normal to said axis for a distanceat least as great as said predetermined depth.
 2. supporting saidmaterial at said surface thereof against a second die surface spacedfrom said first die surface along said axis,
 2. The method of claim 1,including: f. forming said corrugations regularly spaced along saidridge, for curving said sheet material about a single point.
 2. a dieassembly at the opposite side of said strip in opposed relationship tosaid punch member,
 2. supporting same at said surface thereof againstthe surface of a second die element reciprocable in directions normal tosaid path, and
 3. intermittently intercepting said path at a pointbetween said spaced points from the side thereof internal of said arc tobe formed in said strip with a surface of a corrugating elementreciprocable in directions normal to said path; and e. thereafterreleasing said portions by retracting at least said first die elementand said corrugating element in opposite directions normal to said pathfor a distance at least as great as said predetermined depth forpermitting advancement of succeeding portions along said path.
 3. saidpunch member having a punch surface arcuately shaped transversely ofsaid path for forming said corrugation transversely in said ridge, and3. A method of curving an elongated strip having at least one roundedridge extending longitudinally of said strip between opposite ends ofsaid strip, to form an arc therein in the direction of extent of saidridge, comprising: a. supporting said strip for movement along alongitudinal path of travel; b. providing a corrugating station at alocation along said path; c. intermittently longitudinally advancingsaid strip to position successive portions of said strip at saidcorrugating station; and d. at said corrugating station formingcorrugations in each of said successive portions of said ridge,extending transversely thereof by;
 3. intercepting the opposite surfaceof said material and deforming said material against the said surfaceswith a punch surface located therebetween, and e. thereafter releasingsaid material by moving said punch surface and at least one of said diesurfaces from said material in opposite directions normal to said axisfor a distance at least as great as said predetermined depth.
 4. saiddie assembly including a portion retractable in a direction normal tosaid path a distance at least as great as said depth.
 4. Apparatus forcurving an elongated strip having a rounded ridge extendinglongitudinally of said strip, to form an arc therein in the direction ofextent of said ridge, comprising: a. support means for supporting saidstrip for movement in a path along the longitudinal axis of said strip;b. corrugating means positioned at a point along said path adapted forforming a corrugation of predetermined depth in said ridge transverselythereof; c. Feed means for intermittently advancing said strip alongsaid path and positioning said portions of said ridge at said point; d.actuating means for actuating said corrugating means for forming acorrugation in each of said successive portions of said ridge; e. saidcorrugating means including,
 5. The apparatus of claim 4, wherein: f.said die assembly includes a die member reciprocable in directionsnormal to said path for positioning against the surface of said ridge atsaid opposite side of said strip during said forming and retractiontherefrom For a distance at least as great as said depth prior to saidadvancing.
 6. The apparatus of claim 5, including: g. at least onereciprocable wedge member engageable with sad die member for alternatelypositively moving said die member into position against said surface ofsaid ridge and permitting retraction therefrom; and h. means forimparting reciprocating motion to said wedge member.
 7. The apparatus ofclaim 5, including: g. means for imparting reciprocating motion to saiddie member in said directions normal to said path; h. a stationarymember at each of two opposite sides of said die member in slidablecontact therewith; i. a source of lubricating fluid; j. at least oneaperture defined in said die member having a fixed dimension normal tothe directions of movement thereof; k. a conduit for conducting saidfluid to within said aperture including a stationary conduit portionwithin said aperture substantially coextensive with said fixeddimension; l. said fluid being positively urged between opposed surfacesof said stationary members and said die member by said reciprocatingmotion of said die member for lubricating said surfaces.